Sound film reproducing system



April 17, 1945. E. c. MANDERFTELD SOUND FILM REPRODUCING SYSTEM I FiledJan. 26, 1944 I I lo I We wunnq A MMMMl/MM /NVENTOP I E C. MANDERFELD 8VI I aw v I .ATTQRNEV acoustically modulated light .beam' correspondf ingto the widest soundtrack to be reproduced. a light sensitive devicehaving a pair of cathodes disposed-in oblique relation to the light beam-of thecathodes, and niean's forshifting the light beam in adirection-normal to its longer dimento adapt existing apparatus toreproduce both v device and switching .meansin'the circuit for theshifting the lateral position of the lens elements or of the lateralposition of-the fllln. With the able mounting. forltheelements or theoptical Patented Apr. I

PATB TZ FF CE I emsfiuero. Mandel-1e16, mansion assignor v to WeeternElectric Company,-' Incorporated,

j :New Yoria. Y a corporation of York ap licationJamar-iv 2c, 194,Serial,No. 519,742

roas s wi. 179-1003);

This invention relates to scund :tllni reproduc-i ing systems and moreparticularlyto improve! mentsin the method of and-means for obtaininsound reproductionfirom sound tracks 01.

- diiierent widths in the same reproducing appa ratus.

It is the object. or this invention. to provides -.sound filmreproducing apparatus wherein.re- 7 production from sound tracks ofdifierent'w'idths' may. beobtained without necessitating lateralmovement of the or lateral movement of the optical elements ofthereproducing system. A-feature oi the invention lies inthe provisionof a combination of means for producing. an-

with equalareas thereoi projectingonto each.

sion and, masking all but that portion thereof "corresponding to a'soundtrack of reduced width to locate equal ,areas of the reduced light beamon each of device. e In sound fllm reproducing optical systems it thecathodes of the light sensitive is desirable that the optical elementsand the elements defining the film path through-the optical system besupported on fixed mountings, As. is well known, the width of a standardsound track on a sound picture fllm'is' approximately 100 mils. With theintroduction 01 100-mil push-* pull sound tracks, some modifica'tionwas.required the IOO-mllfstandard and the 100-mil push-pullsound track. Thismodification involved' the insystem, the use of a double cathodelightsensitive light sensitive device substantially as disclosed .in UnitedStates Patent 2,094g'Q63, September '28,

- 193mm a. o. Davidsbri. This mod1flcation,how-

ever, did not-require. the' mvision of means for introduction inrecording processes of a ZOO-mil 4 P h-pull sound trackit becamenecessary to pro-' vide a studio reproducer capable" of reproducing from100-mil push-pull or standard. tracks and from a 200-mil push-pull track-Reprodu'cers up ed tor-this pmpoeeinclude-a laterally slid system. -oi?amounting-cums yp 15 .mentsoi the system;

stops to insure the location of the lltical center line .with the centerline of each type Sound track on'flle mm which, together with theslidable mounting, adds considerably to, the cost' 5 of jmanuiactureiandintroduces the disadvantage that the adjustment of the stops mustbeireduently-inspected during operation toinsure em- ,cient operation.

By means of the reproducing system in accord- 1o ance with thisinvention, difi'erent width sound tracks may each be efllcientlyreproduced in the same apparatus by: anovelarrangement. or the elementsof the reproducing system involving no ulateraladiustment of the film orthe optical ele- The invention be more-readily understoodby' reference1to the drawing. n;

which:

- me; 1,is illustration in-perspective. 9 a're- 20 producing apparatusembodying .the lnvention;

Fig. '2 is-aview oi the reproducing system of t FidiIifom the objectivelens photoelectric cell shifted to a diflerent scanwith the light beamning'position; 1 I 7 Fig-53 isa partial view 'of the reproducing systern of Fig.1 showing the position of the light 'lbea-m and an.auxiliary'masking means torreproduction of 100-mil 'standard'soundtrack; and- I *F'ignidiscloses an alternative method of shift- '9 ing'the light. beam in a direction normal to its longer dimension.

Referring to Fig. "1,: the. reproducing optical system shown thereinrepresen'ts a well-known rear-scanning optical system in which acollector 5 lens l-ima'ges the filamentof light source 2. atcondenser-lensll Condenser lens 3 focusses'the aperture of collectorlens I at theplane or film troduction of a central septum in the opticalI cussed,. by means of a relay lens I; .at an" obiec 4 tive lens 5.-'rne objective lens] produces an image "0! the sound track on film 1"at a scan- F. The aperture of .thecondenser lens ,3 is fo-v sllt. linmasking plate I. Allight sensitive push-pull soundtrack which modulates;the 118111 "beaniprolectedtoslitiin'platel. Scannlngsliti 1 1 isprovided with denim-semis ll tofmask 9 the dividing-llnebetweenthehalves or the pllshpull track. .."1he modulated1i8htbeamaftermfl-' ;W L

sensitive device! with the'two cathodes l and- I v I I! each receiving;light beam modulated by, n cesitatesthe proYlsi nof movement. limitingfi halffoi the 200 milp sh pulltrsck. 1 1

the-slit lis two limiting stops 2| and 22.

If the sound track shown on section F2 of the L The light sensitivedevice E is disposed in the light beam in oblique relation thereto, thatis, the axis of the cathodes 9 and it, as represented by line it, isturned in the Plane of the cathodes through an angle with respect toline it nor mal to the light beam.

aeraeeo I While for the sake of simplicity in the drawing the dim F isshown as following a straight ath through the optical system, it will beunder- I stood that the film may .follow a curved path The lightsensitive device 8 is included in a reproducing ci cuit in a well-knownmanner to give pushp reproduotionof the ZOO-mil pushpull sound track.

If it is desired to reproduce from a loo-mil push-pull sound track asshown on section F2 of the film it is necessary only to shift the lightbeam ina direction normal to its longer dimension to a position as shownin Fig. 2, in which the light beam is projected through scanning slit Min plate 1. Scanning slit l4 is one-half the length beam unmodulated bya sound track is masked by the plate 1. Due to the oblique relationbetween the light beam and the cathodes of i the light sensitive device,equal areas of the reduced width light beam corresponding to the IOU-milsound of scanning slit 6 so that the portion of the light track will bereceived by each of the cathodes 9.

and ill for push-pull reproduction. The slit i6 is provided with a.center septum l5 similar to the septum it provided in slit 6.

A means provided for producing movement of the light beam in a directionnormal to its longer dimension comprises an adjustable. reflector I6interposed in the modulated light beam between the objective lens 5 andthemasking plate 1.

The refie'ctor lliis'secured to a shaft ll which may be rotated by meansof a lmurled knob E8. The shaft I! isprovided with a disc l9 having aprojection 20 which is movable to either one of film is a standardIOO-mil sound track, it may be reproduced in the same reproducing systemby the arrangement as shown in Fig. 3, in which the light beam isdirected to scanning slit 5, as in Fig. 1, but in which means areprovided atslit 8 for masking the unmodulated portion of the light beam.The remaining portion of the light beam corresponding to a IOU-milstandard soundtrack is projected to one cathode only of the lig tsensitive device 8. A masking means provided comprises a mask 24slidably mounted in block 25. A machine screw 26 secured in mask 24extends through slot 21 in block to limit the movement of the mask ineither direction of movement.

Fig. 4 discloses an alternative means for registering the modulatedlight beam with either one of the scanning slits in plate I. In thisarrangement, a reflector-30 is fixedly mounted in the optical system.The sound track on the film is scanned longitudinally oi the ill lines,to cover substantially the entire surface 01' 7 this plate /By means ofa movable mask 3| the properaperture may be readily selected for 200-mil push-pull; 100-mil push-pull or 100-mil standard reproduction. Inthe drawing, the mask 3| is positioned-to permit reproduction froni 'alilo-mil standard sound track as slit H and one-.- --hali.' of slit Garemasked. Movement of-mask-v 3| to the right will-open slit [4 andcompletely mask sliti: to permit reproduction only from a "milpush-pullsound track..

It is common practice in optical systems oi the type disclosed herein'toemploy either spherical or cylindrical relay lenses between the plate land the photoelectric cell to focus the rear aperture of objective lens5 on to each of the photo eleptric' cell cathodes 9 and Ill. However, asthe exclusion of relay lenses for this purpose in the drawingaccompanying this specification permits oi a clearer disclosure of theposition of the photoelectric cell with respect to-the modulatedlightbeam, such lenses have been omitted from the drawing. 5

What is claimed is:

' 1. The combination of means producing an acoustically modulated lightbeam, a light sensitive device having a pair of cathodes obliquelydisposed in said light beam to receive equal areas thereof on eachcathode, means for moving said light beam over said cathodes in adirection normal to the longer dimension of said light-beam and,meansfor masking said light beam from an end thereof toagain project equalareas of said reducedlight beam on to each of said cathodes.

2. The combination of means producing an acoustically modulated lightbeam, means for shitting said light beam ina direction normal to itlonger dimension to either of two paths for reproduction, means Iormasking a portion of the length of saidlight beam in one of its shiftedpositions and a light sensitive device provided with a pair of cathodesdisposed in oblique relation to said beam whereby said cathodes eachreceive an equal fractional area of said light beam ineither position ofsaid beam.

3. A sound him reproducing system comprising means for producing anacoustically modulated light beam, masking means interposed in the pathof said beam and provided with a pair of displaced parallel scanningslits of different lengths, means for shifting said light beam in adirection normal to its longer dimension to present said light beam ateither one or the scanning slits in said masking means and a lightsensitive device provided with a pair 61 cathodes disposed behind saidmasking means in oblique relation to the scanning slits therein.

, 4. In apparatus for selectively reproducing film sound tracks ofdiflerent widths, the combination oi means producing an acousticallymodulated over a distance sufficient to produce .an image ail-plate 1gof sufficient size, as represented by the dotted,

light beam corresponding to the widest sound track. to be reproduced, alight'sensitive device provided with a pair or cathodes disposed insaidlight. beam in oblique relation thereto with equal areas oi said beamdirected to each of said cathodes, means for shifting said light beam ina direction normal to its longer dimension and means disposed in saidlight beam in its shifted position for masking all but that portion orsaid beam corresponding to a soundtrack of reduced width whereby-equalareas of said reduced width beam are directed'to' each of saidcathodes:5. In apparatus for selectively reproducing film sound tr'acks ofdifferent widths, the combination otmeansproducing an acousticallymodulated light beam, masking means interposed,in said beams-mi providedwith a scanning slit having its longerv dimension substantially equal tothe widfli cl 9. light corresponding to the widest be reproduced,

sound track to-be reproduced and a second scanning slit having itslonger dimension substantially equal to the width 01a light beamcorresponding to a reduced width sound track,'means for alter- Inatively directing saidlight beam to one or the other of the scanningslits in said maskin means and a light sensitive element provided with aiilurality of cathodes disposedf behind said masking means, in obliquerelation to the scanning slits in the pathof said beam for alternativelydirectin said beam along either of two paths, meansinterposed in one ofsaid paths for limiting the longer dimension'of said beam to correspond20 slit, and means for to the 'smallestwidth, sound track to bereproduced and a light sensitive-device. having a pair J of cathodesobliquelydisposed in said light beam in a manner to receive equalfractionalareas of r said beam on each cathode for each position of saidlight beam. a

'1. In apparatus for selectively reproducing film sound tracks ofdifferent widths, the combination of means producing an acousticallymodulated light .beam corresponding to the, widest sound track to bereproduced, masking means interposed in said beam and provided ,with ascanning slit 10 having its longer dimension substantially equal to thewidth of said light beam and a second scanning slit having its longerdimension substantlally equal to the width of a light beam corsp d n toodes disposed .behind said masking means in oblique relation to thescanning slits therein to receive on ,each of said cathodes an equaltractional area or said light beam from each scanning I selectivelymasking one or ,the other of the slits in said masking means.

mama c. MANDER'FELD.

a reduced width sound track; a 15 light sensitive device'provided withrepair of cath-

